Magnetostrictive LC-circuits as mechanical sensors

Abstract

A remote interrogatable highly sensitive mechanical sensor based on softmagnetic magnetostrictive thin films has been developed. This sensor is very interesting for stress and torque measurements on rotating or hidden objects. It consists of a resonating circuit (LC-tag) with a magnetically sandwiched strip inductor and a thin film capacitor. The resonance frequency of this device is about 500 MHz with quality factors about 8. First measurements with the sensor in a bending test jig have shown high sensitivity to applied strain. A figure of merit (defined as ∆f/f0/∆ε on the order of 1000 could be obtained.